The present invention relates to quick coupling connection devices, more commonly called snap-hooks or snap-rings.
Snap-hooks, which are widely used in industry and for practising mountain climbing, speleology and nautical sports, generally comprise a C shaped body, defining a general flat open ring both ends of which opposite each other define an opening which can be closed by a pivoting finger. The finger is pivoted at its first end on the first end of the body by means of a transverse pivot pin. The second end of the finger, in the closed position of the snap-hook, bears against the second end of the body, the finger being able to be pushed back by the user, by pivoting inside the ring to an open position.
Known snap-hooks form an oblong ring, in which two longitudinal legs may be distinguished disposed along the length of the ring and connected together by two transverse legs forming the ends of the ring. The snap-hook body forms one of the two longitudinal legs and the two transverse legs. The closure finger forms a portion of the second longitudinal leg. This elongate ring shaped structure, in which the body forms the two ends of the ring, means that the snap-hook body withstands the major part of the tractive forces to which the snap-hook is subjected. In fact, in normal use, the snap-hook connects together two tractive elements, for example a first element formed of a piton anchored in a rock and a second element formed of a rope sliding in the snap-hook. At the time of a tractive force, the snap-hook is oriented so that the first element comes into the curvature forming the first end of the snap-hook and the second element comes into the curvature forming the second end of the snap-hook. Both of the traction elements then bear on the inner face of the snap-hook ends, i.e. on the body itself, which then absorbs the greatest part of the tractive forces.
A first problem is due to the fact that, in ordinary snap-hooks, the closure finger is returned to the closed position by a return spring. The return spring is the only element causing closure of the finger, and holding the finger in a closed position. The result is that, under certain conditions of use, some mechanical forces may cause the finger to open. When the finger is open:
the traction elements may escape from the snap-hook, which is then no longer capable of fulfilling its connection function,
the snap-hook becomes less resistant, since the open finger no longer participates in the mechanical resistance, and it may be deformed or even broken more easily.
It has been proposed, to solve this problem, to provide locking means which prevent the finger from pivoting towards its open position. But such locking means require additional handling during opening and/or closing of the snap-hook. This means that such conventional locking snap-hooks are not adapted for example to extreme conditions of use, such as scaling a cliff, since handling thereof requires the use of both hands.
Thus, the problem raised by the present invention is to design a snap-hook in which the application of the tractive load automatically and by itself ensures locking of the closure finger and holds it in a closed position. Thus a self-locking snap-hook is provided.
The advantage thus obtained is that such a snap-hook may be used without requiring the simultaneous use of both hands for opening and/or closing it, while presenting the required conditions of reliability sufficient for preventing the finger from opening under all conditions of use.
In particular, locking is provided, when climbing a cliff face, for example at the time of a fall despite the vibrations which may appear during such use.
According to another aspect of the present invention, the snap-hook may be provided with means for holding the finger in the open position, and causing its automatic return to the closed position as soon as a tractive load is applied to the snap-hook. That considerably facilitates use of the snap-hook, for example in the case when the user must very quickly fit the rope in the snap-hook or wishes to anchor himself to an anchorage element located in a relatively distant position, requiring reaching it with outstretched arm; it is then sufficient to pass the free end of the snap-hook body in an opening provided in the anchorage element, and a simple tractive force on the rope or on the snap-hook causes its closure and locking thereof.
According to another advantageous possibility, attempts have also been made to facilitate opening of the snap-hook in the absence of a load, in order to improve the voluntary unhooking possibilities. Thus, a self-locking snap-hook is provided with assisted opening.
While searching for the ease of closure and/or opening, as mentioned above, the present invention has the further object of designing such a snap-hook allying a great mechanical strength under tractive forces with a great possibility of opening.